1. Field of the Invention
This invention is generally directed to engines or power drive assemblies for small marine boats including water recreational vehicles, emergency and military supply boats and other water craft utilizing outboard engines ranging in size up to 375 horsepower or more and more particularly to power drive systems which modify outboard engines to operate with an inboard capability by converting the conventional vertical drive to an in-line horizontal drive In the preferred embodiment, conventional outboard engines having propeller type propulsion units are converted to jet or fluid propulsion systems by replacing the standard power head adapter plate with a combination adapter and mounting plate which will provided the proper interface of the power head with a tuned exhaust expansion assembly and a gear box assembly which will create a horizontal drive extending from the engine to the rear of the marine craft. Although the power drive assembly of the present invention may be utilized with various types of marine craft, the invention is disclosed as being adapted to a recreational boat wherein the outboard motor is mounted within the boat in such a manner that the entire drive train and engine are carried by a common support base or frame.
2. History of the Art
The small water craft industry has historically utilized both inboard and outboard engines to provide power for propulsion. Until recent years, propulsion was primarily established by means of impellers driven by the power source. In conventional outboard engines, the propellers are commonly mounted to the vertical drive shaft with most innovation in technology being directed toward modifying the drive train and changing impeller design and gearing. Generally, outboard engines are utilized on small boats and have horsepower ratings varying anywhere from approximately 2-375 or more horsepower.
As the small craft industry began to develop new designs for recreational and other type of water vehicles such as JET SKIS and the like, conventional inboard engines were adapted to be utilized as the power source for the propulsion systems for such vehicles. In other conventional recreational water craft, use has been made of outboard engines which are mounted to the transom of the craft in such a manner that the engines may be swiveled to change the direction of the impeller blade to steer the craft or boat. As new power boats or recreational vehicles have gained acceptance with the boating public, new types of propulsion systems have been developed to improve the safety, speed, handling and overall performance and reliability of such boats. One such propulsion system incorporates the use of jet pumps to create a drive thrust.
The development of jet pump propulsion units has enabled recreational boats and the like to h=driven by water thrust as opposed to mechanical propeller drive. Such water jet propulsion units have the advantage of not having any exposed rotating propeller blades associated with the propulsion system. Unfortunately, such jet propulsion units have required the redesign of conventional power and drive systems in order to make the use of such propulsion units possible in small craft or recreational boats.